The present invention relates generally to computer network communication systems and, more specifically, to a multilevel network providing inter-layer multipath redundancy between switches of a first network layer and a second network layer.
Ethernet local area network (LAN) communication networks have been deployed to provide local area connectivity among a number of connected devices as well as wide area access, such as Internet connectivity. Enterprise applications have traditionally required high availability of local devices over the LAN. Ethernet topologies have therefore incorporated high levels of interconnection and redundancy providing multiple paths between local devices and LAN networks. Providing high ethernet reliability typically utilizes the spanning tree protocol (STP), which is a network protocol ensuring loop-free transmission through any bridged ethernet LAN. STP prevents bridge loops while allowing the network topology to include spare (redundant) links serving as automatic backup paths if an active link fails without the need for manual enabling/disabling of the backup links. The spanning tree approach in the ethernet protocol typically creates a transmission path of layer-2 bridges while disabling all potential (redundant) links that are not part of the spanning tree, leaving a single active layer-2 path between any two network nodes. The transparent interconnection of lots of links (TRILL) protocol has also been implemented to enable multipath connectivity either within a data center or among gateways providing wide area network accessed over the Internet. While TRILL also enables a form of Layer 2 multipathing, it does not currently include Layer 3 multipathing solutions. This is a concern when designing high availability networks with redundancy, since TRILL cannot provide the redundant Layer 3 pathing typically assumed by other networking layers; for example, protocols such as VRRP (virtual router redundancy protocol) only allow for one default active Layer 3 gateway router, assuming redundancy will be implemented elsewhere in the network protocols.